Aircraft fuel tanks generally include a fuel portion containing liquid fuel and an ullage portion containing a mixture of air and fuel vapor. The ullage portion should be inerted to prevent or mitigate the possibility of igniting the air and fuel vapor mixture. Various inerting technologies have been employed to alter the chemical composition of the mixture. In particular, inerting may be achieved by either reducing the oxygen concentration to less than 12% by volume and/or reducing the fuel to air ratio to less than 0.03 by weight. As examples, such inerting techniques may include in-flight purging of fuel vapor from tanks and condensing the purged vapor to reduce the fuel to air ratio, or in-flight generation of inerting gas such as nitrogen or CO2 and injection of the inert gas into the fuels tanks to reduce oxygen concentration.
Because these inerting techniques are performed in-flight, energy that would otherwise be available to power the aircraft may need to be used to inert the fuel tank, thus negatively impacting overall efficiency. Moreover, conventional inerting equipment also adds weight to an aircraft, which further impacts efficiency.
Accordingly, it is desirable to provide more effective and efficient inerting of aircraft fuel tanks. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.